采用同步调谐方法的Littman型可调谐半导体激光器
Tunable Diode Lasers in Littman Configuration with Synchronous Tuning

针对采用无镀膜激光二极管的外腔可调谐半导体激光器的跳模现象难以控制的问题,研制了一种采用无镀膜的激光二极管的Littman型外腔可调谐半导体激光器。该激光器通过星型柔性铰链调节反射棱镜的角度,采用带有柔性结构的光栅座调整光栅位置与角度,用粗调与细调旋钮改变激光二极管后端面的位置,利用同步调节激光二极管的注入电流与压电陶瓷驱动电压的方法,通过实验估计确定了激光二极管注入电流与压电陶瓷扫描电压同步调谐比例系数,实现了激光器内外腔纵模同步跟踪,有效避免了跳模的产生。实验结果表明,所研制的Littman型外腔可调谐半导体激光器单纯依靠压电陶瓷电压调谐和二极管注入电流调谐仅能实现约18 GHz与60 GHz的无跳模调谐,而采用同步调谐的方法实现了105 GHz的连续无跳模调谐,频率调谐的扫描频率为20 Hz,满足了激光光频扫描干涉测距的应用要求。
It is difficult to control the mode？？hop of a diode laser without antireflection as light source in an external cavity diode laser. A star？？flexure hinge and a grating mount with a flexure hinge are used to adjust the angle and position of reflector and grating. The position of laser rear facet is changed by coarse and fine adjustments. Mode match of inner cavity and external cavity is realized and mode？？hop is avoided by simultaneous tuning injection current of diode lasers and PZT voltage with the proportionality coefficient from experiment estimation. The result indicates that only mode？？hop？？free tuning of 18 GHz and 60 GHz is achieved by PZT voltage tuning and injection current of diode lasers tuning, while the mode？？hop？？free tuning range is extended to 105 GHz at a scan rate of 20 Hz by simultaneous tuning of the injection current of diode lasers and PZT voltage, thus the performance satisfies the requirement of frequency sweeping interferometer measurement